1. Field of the Invention
The present invention relates to a method for the removal of residual UV radiation-sensitive adhesive from the surfaces of semiconductor wafers, remaining thereon from protective UV radiation-sensitive tapes, which were stripped from the semiconductor wafers. The invention further resides to an arrangement for implementing the removal of residual sensitive adhesive, which remain from tapes (hereinafter referred to as UV tapes) employed as protective layers on semiconductor wafers, particularly wafers having surfaces including C4 connections.
In the present state of the technology which is directed to the manufacture of semiconductor wafers, and especially but not limited to semiconductor wafers, which are employed for the incorporation of collapsed control chip connections (C4s) it is becoming necessary that in view of thermal dissipation problems and packaging requirements which necessitate the employment of thinner dies formed from such semiconductor wafers, that special measures be taken to protect the wafer surfaces and the electronic elements and C4 connections located thereon. Generally, the process of thinning the semiconductor wafers, referred to as C4 wafers, entails the application of a protective adhesive tape as is commonly employed in the industry, onto the surface of the semiconductor wafers having the electronic components and connections located thereon, so as to protect the components and the C4 connections during the semiconductor wafer thinning procedure. Ordinarily, the thinning process is carried out by means of suitable grinding and polishing the obverse or back side of the wafer creating dust and particulate debris from which the front wafer surface is to be protected by the tape. Upon completion of the thinning of the wafer, the adhesive tape is generally exposed to ultraviolet light in order to deactivate the adhesive of ultraviolet light-sensitive adhesive tape and thereby reduce the level of tackiness of the tape to the front surface of the semiconductor wafer on which it is positioned. Upon completion of the tape to UV radiation exposure, which facilitates the release of the tape from the surface of the semiconductor wafer, the tape is peeled off from the front surface of the wafer covering the electronic components and from the C4 connections. However, during the initial wafer taping, or lamination procedure in applying the UV radiation or light-sensitive tape onto the surface of the semiconductor wafer and also during the delamination thereof, i.e., the detaping or tape peeling procedure, problems may be encountered which adversely effect the UV tape deactivation, and which may cause residual adhesive material from the tape to remain on the semiconductor wafer surface.
Among such problems are the formation of gaseous or air bubbles between the surface of the semiconductor wafer and the applied protective tape, which are formed during the lamination of the latter to the surface of the wafer, the formation of UV bulb-like configurations, resulting in a non-uniform lamination being produced about the surface of the semiconductor wafer, and in an improper UV radiation exposure prior to implementing the delamination or peeling of the UV radiation-sensitive adhesive tape from the surface of the semiconductor wafer. As a result of these problems, upon occasion residual adhesive from the UV tape remains adherent to the surface of the wafer and to the C4 connections during delamination and peeling off of the UV tape. The removal of such residual adhesive is quite difficult and not always readily achievable, whereby attempts have been made to utilize a known solvent, such as an NMP, IPA, S/N or the like, which are not always efficacious and frequently fail to remove some or all the adhesive residue. The use of stronger solvents or a process of sputtering may result in damage being encountered by the materials of the electronic components, the C4 connections, aluminum pads on the wafer, and the polyimide composition of the semiconductor wafer during exposure thereto. This, at times, renders the entire semiconductor device being processed non-usable and may lead to economic losses in implementing the manufacturing process.
2. Discussion of the Prior Art
Various publications have to be directed to the application of protective tapes to semiconductor wafers or the like, however, none of which are deemed pertinent with regard to the inventive concept.
David, et al., U.S. Pat. No. 6,872,268 B2 disclose a method of conforming an adherent film and pertains to applying a tape to a substrate and also employing a vacuum to closely adhere the tape to the surface of the substrate.
Yamamoto, U.S. Pat. No. 6,716,295 B2 relates to the application of a protective tape to a substrate and thereafter separating the latter from a substrate by employing a two-tape system for application and then subsequent delamination in an attempt to avoid the formation of tape adhesive residues. However, there is no process of removing such adhesive residues in a simple and clean manner analogous to that of the present invention.
McKenna, U.S. Pat. No. 6,007,654 relates to a non-contact method of adhering a wafer to a wafer tape, and wherein this is essentially implemented in a non-contacting manner through the application of a gas jet which forces the tape against the surface of the wafer or substrate.
Ametani, U.S. Pat. No. 5,310,442 describes an apparatus for respectively applying and removing a protective adhesive tape from a substrate, such as a semiconductor wafer, and does not concern itself with the removal of any remaining adhesive residue through a method analogous with described by the invention.
Mochizuki, U.S. Pat. No. 5,246,533 describes an apparatus for the press-bonding of a tape onto the edges of a workpiece. There is no disclosure of any aspect for removing residual adhesive from the surface of a semiconductor mounting electronic components which were located underneath a protective tape that has been peeled off the surface.
Wellings, et al., U.S. Pat. No. 5,106,439 disclose an application of coverings to a substrate surface, wherein the coverings are applied to the substrate under pressure and/or a vacuum is a sequentially employed manner. There is no disclosure of a method for removing residual adhesive from the surface of a semiconductor wafer, which has remained thereon subsequent to the removal of a protective adhesive tape.
Finally, Nakao, U.S. Pat. No. 4,714,511 describes a method and apparatus for adhering a tape or a sheet to a semiconductor wafer, however, which does not pertain to a method of attempting the removal of residual adhesive from the tape on the surface of the semiconductor wafer.